Domed Greenhouses, Taiyuan Botanical Garden (太原植物园展览温室)

Taiyuan Botanical Garden, in Jinyuan district, occupies land shaped by the coal industry: the architectural press describes a former coal mine, while Chinese sources speak of a coal storage pit turned into a landscaped lake. The client wanted to turn the site into a landscaped park combined with a museum. The scheme by the Viennese practice Delugan Meissl Associated Architects, founded in 1993 and known for the Porsche Museum in Stuttgart, was unveiled in 2016; landscape design went to Valentien + Valentien of Munich, structural engineering to Bollinger + Grohmann and StructureCraft, and building services to Cody Energy Design.

The domes were completed in 2020 (2021 according to Archinect). In August 2020 the local press presented the three greenhouses, likened to 'dewdrops' set beside the lake, ahead of a trial opening on 1 October 2020, National Day, with free admission by reservation. International architecture magazines published the finished project in June 2021. The park, about 2,730 mu or 182 hectares, now holds China's AAAA tourist-site rating. Its programme has shifted along the way: the small dome, which the architects intended for aquatic plants, was presented in 2020 as a rare-plant house and later as a four-seasons flower house.

All three greenhouses are timber gridshells: some 2,400 unique, double-curved glulam beams, supplied by two European manufacturers and laid in two or three crossing layers. The grid is not triangulated; a diagonal network of cables stiffens it, and around 60,000 screws fix the beams at their notched crossings. At the base, steel fittings, each generated from parametric rules, are welded to plates embedded in the concrete foundations. The project followed an unbroken digital chain: drilling positions mapped in Grasshopper were CNC-drilled, and the shell was pre-assembled in panels roughly 6 to 9 metres wide and 9 to 12 metres long.

The double-curved glass includes opening lights for ventilation. The domes face south, and their grid is denser on the north side and more open to the south to catch the sun. Dimensions differ between sources: the largest measures 88 metres across (a free span of over 90 metres according to the architects), 29 to 30 metres high and about 5,500 m²; the smallest is 43 metres across and 10 to 12 metres high; the middle one 54 or 68 metres across.

At opening the three greenhouses displayed more than 1,100 species, in a climate held between 28 and 35°C in summer and 20 to 30°C in winter. The large dome, devoted to tropical rainforest (over 600 species according to a recent guide), is divided into sections: rainforest wonders, simulated plant communities, a waterfall viewpoint, curious plants, a palm garden and tropical aquatic plants; misting equipment wraps a hanging garden in cloud.

The dryland plant house, with more than 300 species, brings together plants from Africa, the Americas, Australia and Asia. The smallest dome, first a rare-plant house, now shows flowers of the four seasons around a landscape that spirals downwards: an orchid gallery, carnivorous plants, hanging plants, and tulips and water lilies in season.

The three domes stand at the edge of the landscaped lake, at the heart of a 182-hectare park with some 25 themed gardens, from peach and plum orchards to an APG systematic garden, a bonsai garden and a butterfly house. The walk continues to the bonsai museum, set into concentric terraces, and to the island restaurant and tea house, whose timber lattice roof draws on Chinese temple architecture. The entrance building houses a natural history museum, and a cantilevered viewing platform with a moving walkway completes the ensemble.